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I have not used Leopard - so this is a real question, not a snarky response. My understanding was that a large part of what makes the whole Time Machine work and worthwhile is the interface. So if you don't have that, isn't it just another backup tool? Let me reiterate - this isn't a rhetorical question. Is doing the same thing without the interface sufficient or is it missing the point?

We've had backup systems for decades. Even Windows has a more functional system than Leopard by accounts I've read. What Leopard did is make backup and restore sexy to the point that people will actually want to do it.

IMO, it is not the _interface_ that is cool about Time Machine, but the ease of use and the fact that it is fully automatic.

I didn't RTFA, so I don't know if this "Time Machine for Linux" implementation is as easy to use or not, but the real thing that makes Time Machine cool is that even my mother can use it.

The Ars Technica article about Leopard has lots of very cool details about Time Machine in it, including how it works. (It uses hard-links, including hard-links to directories, so in each and every time-stamped folder on the backup drive, you have a *FULL* copy of your HDD at that time (minus anything you excluded from the backups). Read that portion of the Ars Technica article if you want answers to questions about it.

Claiming to have created a backuptool "inspired on" time machine obliges one to give some more documentation than... ehm... none.
A few things I know about time machine, which are not trivial:
Every backup in TM is a fully consistend directory tree for which no special software is needed to consult it. Disk space is saved by using hardlinks on the filesystem in a very delicate way, including hardlinks to directories (!!!). As a result, one can very selectively delete backups without corrupting anything. (e.g., you don't want to know the state 11 am, but do want to know the states at 10 pm and 12 pm? easy facilitated without any special software).
TM uses a special feature in Leopard to keep track of modified files and directories, in such a way that TM itself does not have to scan for modified files, but is informed by the OS of modified files. This notification does not even require a deamon process.
Now I do believe one can wrap together something which does backups. But standard unix/linux tools don't offer the above facilities - AFAIK. And rsync certainly does not facilitate multiple hardlinks to a directory to be made. Therefore, this shameless plug probably does not offer something similar to time machine. Unless the author also claims that a Trabant is something like a Ferrari.

I have had this type of rsync backups for years now on personal computers and servers. There are several scripts floating around the internet that do exactly what Time Machine does. The problem is 1) usability and 2) interface.

No end-user is going to put an rsync script in their cron jobs and specify in what mounted partition to store it and then later use rsync to restore the specified files. -- if an end user understands at all what I just said of course

Time Machine's interface is revolutionary. It gives you a way of looking back in time at your own computer and does it in a fancy way consistent with the interface. It does so for any Time Machine enabled application including Mail, Address Book, i*. If you have to restore a piece of mail from backup I doubt you'll know the name of the file it was stored in rsync or any other type of backup let alone knowing how to restore it without removing all the new messages.

Why did we always have to be bashing users for not creating their backups again? Because it was too difficult and too time consuming to make them. Time Machine takes literally 30 seconds to set up and the rest is automated. That's why people will start making backups. It's not difficult anymore and it's going to save me a lot of headaches.

Another thing which makes Time Machine so cool is that it is hooked into the filesystem at a low level. Rather than having to inspect the entire directory tree rsync-style, Time Machine uses the FSEvents interface to stay informed of filesystem changes. FSEvents isn't perfect (it actually only records when a directory's contents have changed) but it beats rsync-ish traversal any day.

In my opinion, without such a method for watching FS changes as they occur (or later, from a log), any hackish solution will fall far short of Time Machine's performance.

It's more of a way to recover your backup tool. So you are right, Time Machine is nothing without the interface. It sucks not being able to recover data easily, and sadly most other tools seems to concentrate on snazy ways to backup, not how to recover.

I don't know whether this Linux implementation does something like it, but what I like most about Time Machine isn't the interface. It's the fact that the backup utility takes care of disk management automatically.

My current backup strategy works something like this:

Set up Retrospect nightly backup scripts.

Happily enjoy the security of having backups for a few weeks.

Wake up in the morning to see an "external disk full" error message.

Procrastinate for weeks while I try to decide whether I'd rather trash the entire archive or find someplace to dump my 80 GB of data (which probably involves making space somewhere, which is always a project).

Finally get fed up with having no backups and just discard the archive.

Return to step 1.

If I were smart and vigilant, I would catch when the archive reaches about 30 GB, and create a new one then, so that managing older archives could be done in more tractable chunks. If I were rich, I would just buy a number of external drives that I would rotate as they filled up. But I am apparently neither, so I just get stuck in this cycle in which I only have a current backup 1/3 of the time, and older archives are randomly discarded or distributed wherever I can find the space.

The great thing about Time Machine is that it consistently fills up my disk with the most relevant backup data: current backups at a high frequency, and months-old backups at a low frequency. When space runs out, the oldest data gets thrown away, but the quantum chunk is a diff between backups, not an entire 80 GB archive.

Apple is a big pattenter... (Espctially after Microsoft stole their interface)

Which they stole from Xerox. Funny. I saw Woz speak, and he stated the following:a) they toured Xerox, and saw everything they did, went home, and made it for cheaperb) Windows "stole" their interfacec) The Creative Labs suit about the iPod interface was silly and unfounded

Hmmm? So any lawsuits AGAINST Apple are silly and unfounded. Those same lawsuits file BY Apple are great and wonderful, huh? Can someone explain this to me?

By the way, I think patenting obvious ergonomic ideas is stupid, and it's not theft to copy an interface. The same way making a car with a steering wheel on the left side is not theft of intellectual property. Apple has, IMO, more mud on their faces because they have the balls to turn around and call themselves moral. And as our president says, "You can't claim the high horse and take the low road."

One of the things that actually make time machine work well is that OS X keeps a log of every file updated on the system, and when the time machine daemon runs it looks at that log and knows which files to back up(as well as what time to mark them with etc). Now, maybe I'm doing rsync the stupid way, but doesn't rsync have to rescan every file on the system to see if it has changed? If you are backing up large directories that could be a large performance hit....

I'm also going to go out on a limb and say that most users don't know where their.MBOX files are, or even what they are. But they'll definitely be missed in the event of a crash.

Or another scenario that's a bit more likely (especially with email inboxes it seems), the mail database gets corrupted, and before you realize it, the automatic backup overwrites the good copy on your backup disk with the corrupt one. I know of a few people this has happened to.

Time Machine is a very good thing, and I commend Apple for it, especially since their old backup app sucked, and wasn't even included in the OS.

Now, how about getting network backups to work properly, and patching Time Machine to gracefully deal with large files?

time machine does not use ZFS. In fact, Leopard as shipped cannot write to ZFS partitions. ZFS would be the "correct" way to handle it, there current implementation is a hack, as this rsync implementation shows. It's the type of solution you'd expect from a project in an Advanced OS course.

Yes, they have a nice sexy inteface (and that's good and all), but in truth there interface isn't really that amazing. For most people, microsoft shadow copy interface is just as usable.

Dirvish looks nice, but has the same problem so many cool Linux tools have. It stops short of being a backup "for the rest of us". An approachable GUI is important to most computer users as well as a "set it and forget" it maintenance cycle.

However, most importantly hard links on directories were added to the OS so that entire unchanged directory trees would not be reproduced. This significantly reduces the number of files needed on the backup drive.

Hard to beat the Time Machine setup scenario: 1. Click the big ON button; 2. Pick a disk driveDone:)

IMO, it is not the _interface_ that is cool about Time Machine, but the ease of use and the fact that it is fully automatic.

I didn't RTFA, so I don't know if this "Time Machine for Linux" implementation is as easy to use or not, but the real thing that makes Time Machine cool is that even my mother can use it.

So it is the interface, then?

I realize the interface doesn't do the heavy lifting in an application, but I wish the FLOSS crowd would finally clue in to the fact that ease-of-use matters. For example, GnuPG is a way to protect your privacy through encryption, but it only has a CLI. GUIs exist for GnuPG, but their installation is complex. Why do people work on GnuPG? Because privacy is important! But who gives a fuck when only 1% of the population can use it? Thanks for nothing, GnuPG!

I have no particular bee in my bonnet about GnuPG, it was just the latest FLOSS effort to piss me off. Open-Source software and "Free as in Freedom" are ideas too important to be relegated to the technical elite, but the technical elite's refusal to make their tools easy enough for the rest of us cuts out most of society. You have the cure for cancer but refuse to give it to us because we don't have the time or desire to learn Perl.

This Linux "Time Machine" sounds cool. Too bad I'll never be able to use it. Bah!

You're exactly right. It is missing the point without the interface. The real breakthrough in TM's UI isn't that the user can go retrieve a file as it was last week (with gratuitous 3D effects), but rather that they can go retrieve something that isn't a file.

What if you deleted that email you really wanted, or made a bad edit to a contact in your address book, or a photo in iPhoto/Picasa? These apps store lots of data in some kind of database. As a geek, you know that you need to find this database, move the current one aside, restore the old one, export the content you want from the app, move the current database back into place, and import the content you just extracted from the old database.

With TM, Your Mom opens Mail, and presses the TM button. She gets the same 'windows through time' view, listing her mailbox at each checkpoint. She selects the message(s), and hits the restore button, and it gets brought into the current database. She doesn't care how it gets represented on disk.

I have an honest question that no one seems to have answered. What is so exciting about 'time machine?' It is being extolled as new and groundbreaking, but I don't see much, if any of a difference with the 'previous versions' option within Vista, or 'shadow copy' which can be used in a network environment with XP and server 2003.

Both of those windows-based solutions, which have been out for quite some time, allow you to restore an individual file or folder from a wide range of dates. My setup backups files at midnight and 9am everyday, and I can any version of a file going back nearly 3 months. If I were to reduce the backups to once daily, 6 months of version changes on each file is plausible.

The only arguement I can find about why Time machine is innovative is comparisons between it and system restore on the PC. Since these are two entirely different functions, I don't understand why its brought up.

Time Machine's ability to simply browse backwards through time in the folder, whilst still having the folder functionality usable is far beyond BackupPC. Indeed I bet there are many times that you just want to do this, you don't want to restore the file or the folder as it was then, you just want to quickly glance inside the file as it was.

There's nothing amazingly clever about Time Machine, but it is Apple "Getting It Right(tm)" interface-wise (excluding silly starfield, etc) and functionality-wise.

And yet, the FOSS community seems to think that everyone should be using FOSS. You can't have it both ways -- either FOSS is only for geeks and large corporations, in which case it will never catch on with the consumer; or it is for everyone, in which case the geeks advocating FOSS need to make sure it can work for everyone. Otherwise, comments about how everyone ought to be using FOSS are hypocritical.

A number of people have pointed out some of the major deficiencies of this software in comparison to Time Machine. There are a couple of items, however, that no one seems to be mentioning and which I think will have some of the biggest, long term effects. First, Time Machine includes easy APIs so that other programs can access the stored data from within their application. Second, it is included in the standard install so developers can rely upon it being there.

Why does this matter? Think of all the applications in which versioning would be really nice, but it just isn't available. Your address book, for example can look up old contacts or numbers or addresses. Your development tools can automatically load an older, version of that code you're writing to recover that function you did not think was needed anymore, even if you did not write it to a versioning server. Your video games can take you back to older saved games or versions of characters before you sold that really cool item. Photoshop, Word, OpenOffice, etc. can use it to revert changes to a file all the way back to last month.

The difference is that while many users will never take the trouble to learn how to use a backup system and properly recover an old version of a file, they might trouble to plug in a Time Machine drive and then use the interface to backed up versions from with their applications. It seems strange that everyone is ignoring the cool new API for developers and concentrating on the integration in the finder, which will probably be the lesser used portion of Time Machine.

1) Time Machine uses the FSEvents daemon to keep overhead to an absolute minimum
2) Time Machine uses file and directory hardlinks to minimize space taken, but provide a complete, usable, identical directory structure to the original
3) How to you do previous versions on a deleted file?
4) Time Machine provides a minimalist, automatic, and "easy-to-use" backup solution that people want to use. Making people want to use backup software is a coup in itself.

The biggest and most exciting thing to me about Time Machine is the plug-in system. Time Machine itself can just restore files. But the plug-in system looks like it allows the application to extract individual pieces of data from within backed-up files, and to treat a set of files as one unit for browsing purposes. Plus, there's the QuickView tie-in allowing apps to preview the contents of a backup.

If Vista's actually does work that well, then you've asked a very interesting question.

Somehow, though, I don't think Microsoft suddenly woke up and figured out how to actually be fanatic about making minor hassles vanish. I'm betting Vista's feature works that well *after* you mutter the right keyboard and mouse incantation, with a lot of "well, of course"ing from people who just overwhelm them (the hassles) with competence, from the user side of the equation, and simply cannot comprehend the notion of doing it from the software end.